The Senate on Wednesday failed to advance a bipartisan background check proposal that Democrats had hoped would be the core of any bill.

The background check legislation, championed by Democrat Joe Manchin III of West Virginia and Republican Patrick J. Toomey of Pennsylvania, received only 54 votes, six short of the 60 needed to clear a threatened filibuster. However, the measure does have 55 Senate supporters, given that Senate Majority Leader Harry Reid, D-Nev., changed his vote at the last minute to preserve his ability to call up the vote again.

In addition to Toomey, only three Republicans — Sens. Susan Collins of Maine, John McCain of Arizona and Mark S. Kirk of Illinois — voted in favor of the background check compromise.

Besides Reid, four Democrats voted against it, including Sens. Max Baucus of Montana, Mark Begich of Alaska, Heidi Heitkamp of North Dakota and Mark Pryor of Arkansas.

In the 24 hours leading up to the vote, President Barack Obama and former Rep. Gabrielle Giffords, D-Ariz., along with her husband, Mark Kelly, had personally lobbied on-the-fence senators or those who had declared themselves as “no” votes. But those efforts failed.

Manchin, who delivered a floor speech earlier Wednesday, begged his colleagues to read the bill, emphasizing that it specifically prohibited a federal gun registry. Many opponents of the bill had cited a fear of a gun registry as their reason for voting against it. On the floor, Manchin burnished his National Rifle Association membership card to try to flaunt his pro-gun credentials before attacking the group.

“I agree wholeheartedly with the goal of the NRA,” Manchin said. “I was surprised when the latest alert from the NRA was full of misinformation. ... They are telling members that our legislation would criminalize the private transfer of firearms by honest, law-abiding citizens. ... That is a lie.”

Hours before the vote, most of the backers of the Manchin-Toomey bill were openly resigned to the fact that it would fail. The only person who seemed to hold out some hope that senators would have eleventh-hour conversions was White House Press Secretary Jay Carney, who told reporters in his daily briefing, “There is an opportunity for 60 senators to do the right thing.”

Though the background check provision garnered the most attention, other gun violence measures, such as the assault weapons ban or limit on high-capacity magazines, are also expected to see defeat Wednesday.

As the Senate voted down the background check compromise, relatives and victims of recent mass shootings watched from the gallery, a reminder of the emotionally charged advocacy that came to the Hill but failed to move senators.